Warming won't give emperor penguins happy feet

Emperor penguins might not have happy feet, after all. The first analysis of their genome indicates that they may not handle climate change well. But the only other Antarctic-breeding penguin Adélie penguins, being more adaptable, might have something to squawk about.

Male emperors are known for incubating their eggs under a flap of skin over their feet through Antarctic winters. Because they nest almost exclusively on sea ice, they might be particularly vulnerable to climate change.

Now David Lambert of Griffith University in Brisbane, Australia, and his team have analysed the first two penguin genomes, of an emperor penguin and an Adélie penguin, which they first sequenced in 2011.

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The analysis has allowed Lambert to create a picture of how the two species’ populations have changed between 10 million and 10,000 years ago, during warm and cool phases.

Boom and bust

The team compared the amount of genetic variation at various points on each of the penguins’ chromosomes. At times of population expansion there would usually have been more genetic differences between individuals, with the opposite true in hard times. These genetic crashes and booms leave traces in the genes.

It seems that Adélie penguins were able to expand in numbers during warm time periods. Because they build rock nests on ice-free ground, they were probably able to take advantage of the extra breeding sites, Lambert says. In contrast, emperor penguins populations stayed fairly consistent during the time Lambert analysed.

For instance, Adélie numbers tripled from about 20,000 to about 60,000 during a period of warming between about 150,000 and 60,000 years ago. During that same period Emperor numbers hovered around 10,000 to 20,000.

Since Earth is set to warm rapidly over the next century, this is “bad news for emperors, but ironically potentially good news for Adélies”, says Lambert.

In the long term, emperors are in the firing line because they nest on sea ice, says Lambert. “I don’t think they will adapt. I think they will go extinct.”

Fall of emperors

Yet perhaps we shouldn’t write off emperors just yet. Scientists “don’t really have a handle on how emperors’ behaviour might alter” in the shorter term , says Phil Trathan of the British Antarctic Survey.

Gemma Clucas, who studies penguin populations at the University of Southampton, UK, agrees. The consistent emperor’s populations depicted in Lambert’s results could be “evidence that emperors are much more flexible than we’ve given them credit for,” she says. Although she agrees there may be a threshold of warming beyond which they might not be able to adapt.

Trathan says it would be worth collecting genomes from more than one individual from each species. In particular it would be interesting to compare penguins from different regions, he says.